Are OTPs approaching custom standards?

if they don't look after their body, that'd probably happen,

Not totally true Ed.

Your dad is not just fit, he's also lucky. Being fit when younger is easy. But its hard to fight genetic make-up, or a rapidly slowing metabolism.

The "middle-aged spread" can be explained from a bio-physiological perspective also; as can bone shrinkage, stiff joints...etc.